Insensitive Munitions must be developed to improve the combat survivability of an armament vehicle. It has been found that munitions utilized in some weapon systems are vulnerable to sympathetic detonation. For instance, the cannon caliber ammunition stored aboard these vehicles is vulnerable to initiation via shape charge jet and then propagation of the reaction due to sympathetic detonation.
This sympathetic detonation and propagation scenario can be summarized as follows: if a round is hit by a shape charge jet, it is initiated. As a result, the fragments that are generated by the blast then strike the other rounds that are adjacent to it. The latter rounds then initiate, contributing to the overall reaction and damage sustained by the vehicle, crew, and other munitions. The mechanisms of reaction for the initiation of the surrounding rounds are due to the blast and fragments impinging on the aforesaid adjacent round. The probability of sympathetic detonation can be reduced in several ways. This can be done by reconfiguring the ammunition compartments within the vehicle. It can also be accomplished by packaging the ammunition with anti-fraticide materials. However, each of the aforesaid solutions will reduce the amount of space available for the storage of ammunition. The most acceptable solution to the problem is to reduce the sensitivity of the energetic material to sympathetic detonation Incorporating less sensitive energetic material will reduce the vulnerability of initiation from the cited threats without reducing the number of rounds stored in the vehicle. It has been found that by reducing the vulnerability to sympathetic detonation of the energetic materials used in these munitions, the probability of catastrophic reaction can be minimized.
However, the development of explosive compositions for military applications is also motivated by the need for insensitive explosives with high energy output. This problem has always plagued the military, but in recent years it has become more critical. Increased performance requirements on munitions are making it necessary to utilize higher energy explosives. Consequently, explosives tend to become more sensitive and vulnerable to sympathetic detonation as the energy content of the formulation increases.
Explosive compositions have traditionally been developed along three basic avenues. The first of which takes an energetic filler such as cyclotrimethylene trinitramine cyclotetramethylene tetranitramine, pentaerythritol tetranitrate, etc, . . . , and combines it with an energetic binder such as trinitrotoluene or nitrocellulose. These compositions exhibit high energy output with lower concentrations of energetic filler but they tend to be too sensitive for new military applications. The second approach is to combine a high percentage of explosive filler in an inert binder usually an organic wax or polymer. By varying the percentage of explosive filler, the sensitivity and energy output of the material can be changed. Typically, one can improve the vulnerability of the composition by lowering the concentration of filler but this will also lower the energy output. The objective then becomes finding the concentration of binder that lowers the sensitivity to an acceptable level while maintaining as high an energy output as possible. The third approach is to synthesize new energetic molecules.
The explosive formulations developed to date using the techniques described above have not yielded high energy output explosives that demonstrate a low enough susceptibility to sympathetic detonation to be considered for use in insensitive munitions. Previous efforts have failed in this respect in that they did not discover the proper combination filler or binder (i.e. in either chemical type or concentration level) to yield these properties.
The result of this invention is a high energy output explosive which is comparable to PBXN-5 having a composition of 95% HMX and 5% of an inert binder. The latter composition is the conventional explosive utilized in cannon caliber ammunition. The advantage of this invention over PBXN-5 is that the new explosive composite demonstrates a sharp reduction in the vulnerability to sympathetic detonation.